Download a file with pure Capacitor FileSystem and the Fetch API.

pure-downloaded-capacitor.js

const downloadFile = async (uri, path, folder) => {
	return new Promise(async (resolve, reject) => {
		try {
			const file_request = await fetch(uri, {
				method: 'GET',
				credentials: 'include',
				mode: 'cors',
			});
			const file_blob = await file_request.blob();

			const reader = new FileReader();
			reader.readAsDataURL(file_blob);
			reader.onloadend = async () => {
				await Capacitor.Plugins.Filesystem.writeFile({
					path: path,
					data: reader.result,
					directory: folder,
					recursive: true,
				});
				resolve(true);
			}
		} catch(err) {
			reject(err);
		}
	});	
}

// Use it like
(async () => {
	await downloadFile('https://example.com/hello.zip', '/hello.zip', 'DATA');
})();

Thank this was really helpful
edit: although FileSystem should be Filesystem it took me a while to figure it out

I just fixed that, my bad, (I know I am like 7 months late, my bad - never saw this!